Process and means for abrading bodies



Nov. 24, 1942. [MELMANN 2,303,276

PROCESS AND MEANS FOR ABRADING BODIES Filed March 2'7 1941 Patented Nov. 24, 1942 OFFICE PROCESS AND MEANS FOR ABRADING BODIES Henry Louis Imelmann, Chicago, Ill.

Application March 27, 1941, Serial No. 385,396

4. Claims. (01. 51-71) This invention relates in general to a process and apparatus for accurately. shaping small bodies, and more particularly, to a process and apparatus for producing precision shapesv of predetermined dimensions on the ends of small bodies, such as required for the points of phonograph and. writing styli, instrument pivots and the like.

The ends, or points, of articles of this character are usually made from relatively hard materials, such as hard metal, hard metal alloys, or crystalline material, such as the sapphire.

Prior to this invention the points of such articles were produced by first rough shaping the points by well known machine and, abrading methods and then applying a finishing operation by subjecting, a quantity of the. pointed articles to tumbling in contact with abrasives. The tumbling method is costly and inadequate principally because of the lack of uniformity in the final shape'and character of the finished product, and further, because the tumbling operation produces a multitude of microscopic facets on the surface of the points of the articles which are undesirable from a frictional standpoint whenthe articles are used for th purpose intended.

The above objections are completely overcome in the present invention through the novel process and means for producing pointed articles of microscopic uniformity and precision smoothness.

The principal object of the invention is a process for automatically abrading to a predetermined size and shape a substantially spherical polished surface upon the end of a pointed body.

Another object of the invention is th provision of apparatus for abrading pointed bodies to a predetermined size and shape, including means for attacking the end of the pointed body with moving abrading vanes.

A further object of the invention is the provision of a process and means for abrading pointed bodies to a predetermined size and shape by successively attacking the end of the pointed body with a plurality of moving abrading vanes while the end of the pointed body is rotated about its principal axis.

With these and other objects in view, the invention consists of the novel process and means described, one embodiment of which is illustrated in the accompanying drawing, in which:

Fig. 1 is a greatly enlarged fragmentary perspective view of a body having a rough-shaped end.

cipal parts of an abrading machine for shaping the pointed end of the body shown in Fig. 1. I

Fig. 3 is a plan view of the principal parts of the machine illustrated in Fig. 2. Fig. 4 is an'enlarged diagrammatic view of th end of the body shown in Fig. 1 in relation;to four positions of an abrading elementof th ma-, chine shownin Fig. 2.

Fig. 5 is an enlarged View of the end of the body shown in Fig. 1 after abrading. I Fig. 6 is an enlarged cross-sectional view of the; body shown in Fig. 5 taken through section line 6-6, Fig. 5. l Although the process and apparatus described; hereinafter in this invention are applicable...to. the shaping of a large variety of bodies, the shap ing of the points of phonograph styli will be used as an example. i t An enlarged fragmentary view of a typical,

phonograph stylus having a rough pointed end. is

shown in Fig. 1, comprising a pointed shank -I, terminating in an integral point 2 of harder ma-. terial. The workingflend, or point, of a phonograph stylus must terminate in a substantially spherically shaped surface of precise predeter-.. mined micrometric dimensions in order to insure proper operation'for the use intended. f

' This'process is dependent upon an automatic machine for producing such points. The princi: pal elements of the machine are illustrated in Figs. 2 and 3, wherein the stylus l to be abraded is inserted and held in a chuck or collet 3 which isadapted to be'rotated in its fram 4 by means not shown. An abrading Wheel 5, mounted on shaft 5, is positioned a suitable distance from the collet 3 and adapted to be rotated, by means not shown, about an axis substantially at right angles to the axis of rotation of the collet -3. A plurality of flexibile abrading vanes l, of uniform length, are secured about the wheel 5 normally in radially-spaced relation with each other. Each of the vanes I is coated with a suitable abrasive material 8. The pointed end of the stylus to be abraded is retained in the collet 3 in the path of rotation of the free ends of all of the vanes I.

Fig. 3 shows a plan View of the previously described elements in their normal relationship.

The shaft 6, which supports and rotates the wheel 5, is also adapted to be reciprocated longitudinally along its axis (as shown by arrow) a'distance less than the width of the vanes 'l. g

The process for forming a uniform predetermined substantially spherical surface to the point Fig. 2 is a diagrammatic elevation of the prin- 55 of a rough shaped stylus consists of securing the in the path of the abrading vanes I and then rotating the collet and stylus together about their .axes and simultaneously rotating the wheel about the axis of its shaft 6.

It is now apparent that each of the flexible abrading vanes I will successively strike and abrade the pointed end of the stylus in a manner illustrated in Fig. 4. Each van will first strike the pointed end of the stylus at a predetermined angle with respect to the axis of the stylus, and continued movement will cause the vane to flex and assume an ever-increasing tangent angle with respect to the ,axis of the stylus until the outer end of the vane has moved out of contact with the stylus. Four of the many positions assumed by each vane are shown at a, b, c, and d, Fig. 4.

It is thus obvious that the rotation of the stylus and the successive attack of each of the vanes 1 upon the point of the stylus will abrade and polish the stylus point to a precise predetermined substantially spherical surface, the radius of the spherical surface being dependent upon the hardness of the stylus material, the physical properties of the abrasive used, the speed of rotation, and the time the abrading action is permitted to function. Reciprocation of the abrading wheel 5 along its axis during its rotation is provided to distribute the wear of the abrading material on each vane over substantially the entire width of each vane.

It is apparent that an alternate construction wherein rigid abrading vanes are secured and hinged at the rim of the wheel will produce a similar result and is intended to be within the scope of the appended claims.

Figs. 5 and 6 illustrate the character of the end of a body following the above-described abrading operation and the spherical point attained.

It is also apparent that substantially elliptically-shaped points may be obtained with the above process by applying uniform acceleration and de-acceleration to the rotation of the collet 3 and hence to the body retained therein.

Having decribed my invention, I claim:

1. The process for abrading the end of a pointed body in which the said body is rotated by power means about its principal axis and the pointed end thereof is simultaneously subjected to contact with a flexible, flat, moving abrading element, the said rotating body being held in fixed relation with the path of movement of the said abrading element and having its pointed end projecting into said path, whereby the point of contact of the abrading element with the said pointed end describes an arcuate path during the said contact with a flexible, flat, moving abrading element to abrade the end of a pointed body to a predetermined shape.

2. The process for abrading the end of a pointed body in which the said body is rotated by power means about its principal axis with its pointed end projecting into the path of a plurality of flexible, flat, moving abrading vanes, said rotating body being held in a fixed relation with said moving vanes substantially normal to the path of movement of said vanes, whereby each of said vanes successively abrades the said pointed end of said body for a predetermined period, the relative movement between the abrading vanes and the end of the pointed body arranged whereby the abrading contact between each of said vanes and the pointed end of the body describe an arcuate path with respect to the principal axis of the said body during the said abrading period of each said vane to abrade the end of a pointed body to. a predetermined shape.

3. An apparatus for abrading one end of a pointed body, comprising a driven abrading means having a flexible. flat abrading element resiliently afiixed thereto, said element arranged to move in a predetermined path, positioning means for holding the said body for rotation about it principal axis with the said end of said body projecting a predetermined fixed distance into said path, power means for rotating said body when held in said positioning means, said abrading means and said end of said body positioned with respect to each other, whereby the said abrading means will periodically attack the said end of said body in an arcuate manner with respect to the axis of rotation of said body when the said body is rotated while the abrading means is driven to abrade the end surface of the said pointed body to a predetermined shape.

4. An apparatus for abrading one end of a pointed body, comprising a driven abrading means having a plurality of spaced flexible, flat abrading elements secured thereto, said elements resiliently extending from said means, each said element adapted to move in a predetermined path, positioning, means for holding and also rotating said body about its principal axis a predetermined fixed position into said path. the abrading means and the said end of said body positioned with respect to each other whereby the end of said body will be periodically attacked by each of the said elements in an arcuate line of contact with respect to the axis ofrotation of said body when the abrading means is driven and the body is rotated to abrade the end surface of the said pointed body to a predetermined shape.

HENRY LOUIS. IMELMANN. 

